Practise Finding the Coordinates of the Midpoint of a Line Segment

We can find the midpoint of a line segment  by using the mean average of the endpoints for x and again for y.

For Example

Find the coordinates of the midpoint of the line segment whose endpoints are at (-2, -3) and (4, 5)

Answer

For the x coordinate of the midpoint - The average of -2 and 4 is (-2 + 4) ÷ 2 = 2 ÷ 2 = 1

For the y coordinate of the midpoint - The average of -3 and 5 is (-3 + 5) ÷ 2 = 2 ÷ 2 = 1

So the midpoint of the line segment with endpoints at (-2, -3) and (4, 5) is at (1, 1)

In this activity, we are going to find one of the endpoints when given one endpoint and the midpoint.

Example

A and B are the endpoints of a line segment and M is the midpoint.

Find the coordinates of endpoint B.

Answer

x coordinate: 

From A to M is 2 moves to the right. Therefore, if M is the midpoint, then B must be 2 moves to the right also.

y coordinate:

From A to M is 3 moves up. Therefore, if M is the midpoint, then B must be 3 moves up too.

Therefore, the endpoint B is at (5, 8)

Does that make sense?

Let's have a go at some questions. Remember that you can look back at this introduction at any point by clicking on the red button on the screen.